In time-division switching systems a plurality of calls are simultaneously accommodated by momentarily connecting via a time-division bus the parties involved in each call during that time slot assigned to that call. Each momentary connection is effected through the closure of a plurality of normally open line switches, each such switch being dedicated to a different party connected to the system. Typically, the closures required during each time slot are accomplished by a line switch controller in response to the enumeration of a recirculating time slot counter responsive to the pulses from a clock pulse source. Also, some form of memory is usually required to record which parties are connected during each time slot in order to permit ready control. Since the line switch controller is separate from the memory, an ambiguous situation can arise if a timing or memory error is made. For example, if the time slot assignment for a particular party is incorrectly entered in memory, the party is connected during a different time slot than expected by the system.
It is an object of this invention to eliminate ambiguous control situations arising in time-division switching systems having a separate line switch controller and assignment memory.
It is a further object of this invention to incorporate the line switch control and slot assignment memory functions in a single apparatus.